An endmill, for example, has been used for cutting of materials that are generally taken as difficult-to-cut materials, such as nickel-base heat-resistant alloys. For end milling of difficult-to-cut materials, a cutting tool with a cutting edge having split portions called nicks has been proposed (for example, PTDs 1-3). By providing nicks in a cutting edge to make the cutting edge discontinuous, swarf is split to reduce cutting resistance and reduce temperature rise of the cutting edge.